Purifying solid materials esp. contaminated gypsum - by finely grinding and subjecting to flotation treatment to separate cyanide and cadmium cpds. etc. as recoverable froth

摘要

A process for purifying contaminated solid materials, esp. gypsum, using water, comprises (i) finely milling the contaminated material, (ii) subjecting the finely milled material to a flotation treatment and (iii) recovering the treated material in the known way. Pref. the contaminated material is milled to a particle size of 20-70, esp. 40-50 micrometres and flotation is carried out at 0-50 deg. C, esp. room temp., using a surface active agent. The process allows removal of impurities such as cyanide cpds. and Cd cpds. from solid materials such as gypsum by a simple method which does not require advanced equipment, reduces environmental pollution, esp. of ground water and surface water, and gives the impurities in a form making industrial recovery attractive.